Robotic vs Laparoscopic Gastrectomy for cT4a Gastric Cancer

Inclusion Criteria: Histologically confirmed gastric or Siewert type III (and selected type II) gastro-oesophageal junction adenocarcinoma, clinical stage cT4a without bulky lymph-node enlargement on contrast-enhanced CT or MRI No prior neoadjuvant chemotherapy, radiotherapy, or other anti-cancer therapy Tumour deemed amenable to R0 resection by a board-certified gastric surgeon and radiologist ECOG performance status 0-1 Estimated life expectancy ≥ 6 months Adequate organ function defined by: * ANC ≥ 1.2 × 10⁹/L, platelet ≥ 100 × 10⁹/L, Hb \> 8 g/dL (no transfusion/G-CSF within 14 days) * ALT/AST ≤ 2.5 × ULN, total bilirubin ≤ 1.5 × ULN (or isolated indirect hyperbilirubinaemia) * Serum creatinine ≤ 1.5 × ULN and calculated creatinine clearance ≥ 60 mL/min * INR or PT ≤ 1.5 × ULN (therapeutic low-dose anticoagulation allowed) * TSH and free T4 within normal limits or clinically insignificant deviation BMI ≥ 18.5 kg/m² or body weight ≥ 40 kg Signed informed consent Exclusion Criteria: cT4b disease, distant metastasis, or peritoneal cytology positive for malignancy Bulky lymph-node conglomerates (\> 3 cm short axis) or N3 disease precluding D2 dissection Previous gastrectomy or major upper-abdominal surgery (except uncomplicated laparoscopic cholecystectomy) within 5 years Concurrent malignancy within 5 years (except adequately treated basal-cell carcinoma, carcinoma in situ, or stage I tumours) Gastric cancer arising from emergency presentation (bleeding, perforation, ob…